Humans are thought be the only species that have asymmetrical brains. It is this specialisation between the sides of the brain that may have been an important factor in the development of language. Now, one researcher is suggesting that brain symmetry is important in mental illness.
Professor Crow, who works at the Schizophrenia Research Institute, suggests that it is a lack of asymmetry in patients with schizophrenia which is at the root of their mental illness. Psychoses could be a result of information leaking from one part of the brain to another. This may cause, for example, internal thoughts to be experienced as real external voices.
Genetics have a large role to play in brain development and so Professor Crow’s research is concentrating on this area for the root causes. Still, while a genetic component will probably be important, other factors such as social and environmental are also going to play their part. 
BBC NewsSome evidence that non-human primates have asymmetrical brains.
